Feb. 11-12 2019 Wintry Mix Event

I wish I’m able to understand every little thing all of you guys, pros do. I mean im 18 i do my best to watch, listen, learn! Definitely love snow, and for what i can see it looks good from here until perhaps 9:00 as you said SENJ

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4-5" works for me. Heaviest band over us right now should drop 2" alone. We'll see if kids get a closing, a delay is a def.

Unless there is something drastic that shows up in the high res models today this is a now cast forecast. Overall this has progressed as planned. Everyone should see at least a little snow tomorrow. Enjoy the day.

NWS has issued a Winter Weather Advisory for Central NJ for 2-4” of snow then mixed sleet and frz rain midnight tonight through 7 pm tomorrow. Forecast to impact both rush hours.

What a warm tongue on the rgem and latest n a m. It's about an hour of snow and then a sleet Fest until it changes to rain

Here is the NWS Mt Holly discussion this morning. If you’re wondering why as Scott said above this is a nowcast situation read the bolded first line with emphasis:

This is one of the most complicated forecasts of my admittedly short career, largely owing to logistics, but lack of physical understanding regarding what will transpire tonight through tomorrow night is not far behind. We start with
watch/warning/advisory decisions this morning:

(1) Based on collaboration with CTP, BGM, and OKX, we will
continue the winter storm watch as is for Sussex (NJ), Carbon,
and Monroe Counties. This is based on remaining uncertainty with snow and ice amounts Tuesday and Tuesday night.

(2) Berks, western Montgomery, upper Bucks, and Lehigh Counties will be in a winter weather advisory from this evening through early Tuesday evening based on expected onset of wintry precipitation tonight and transition to mostly rain by Tuesday evening.

(3) Hunterdon, Somerset, Middlesex, Monmouth, and Mercer
Counties will be in a winter weather advisory from midnight
tonight to early Tuesday evening.

(4) Northampton, Warren, and Morris Counties will be in a winter weather advisory from midnight tonight to 1 am Wednesday.
(2)-(4) are based on the general onset timing and precipitation
transition of the latest NAM, NAM Nest, and hi-res simulations.

Forecast was based largely on a consensus blend of the coarser and hi-res 00z/06z models, though additional weight was provided to the NAM/NAM Nest, owing to its preferred evolution of the low-level thermal profiles (and its generally good performance in warm-advection events like the upcoming one).

In general, the overall thinking with precipitation Monday night
through Tuesday night has not changed considerably.
Unfortunately, this means that a large amount of uncertainty
remains, primarily with timing the changeovers from snow to
sleet to freezing rain. The general idea is for snow to spread
northeastward into southeast PA and adjacent portions of
southern New Jersey during the evening, followed by central
portions of New Jersey and eastern PA by or after midnight. As
strong advection continues during this period, a warm nose will increasingly lead to a transition to sleet and/or freezing rain. This looks to mainly occur late tonight and Tuesday morning, generally near/north of the I-76 corridor (precipitation mostly rain to the south). Mixed precipitation will spread rapidly northward during the morning hours, and may linger through at least early afternoon near and especially west of the Philadelphia metro area. Eventually, warmer air will surge sufficiently northward to scour the cold air south of the I-276/I-195 corridors during the afternoon (at least, that is
what is forecast), but the cold air may prove to stick around
much of the day in the Lehigh Valley and northern New Jersey.

There are two main uncertainties to address, should the timing
above be in the ballpark. (1) How much of the precipitation
occurs as snow versus sleet versus freezing rain? (2) Are the
models handling the lingering surface cold air adequately? My
inclination is that snow accumulations may be hindered by
residual dry air from a stubborn surface high to the
north/northeast. However, once the precipitation gets going,
large-scale lift will be strong, so the snow may become moderate to heavy at times before transition to a mix. The sleet signal may also be overdone given the strength of the warm advection aloft. The warm nose may become quite pronounced, especially if cold air damming is as strong as (say) the NAM suggests. This certainly makes me worry about icing potential, especially in the far north (generally near and north of I-80). Though considerable uncertainty remains with relative amounts of each precipitation type, the combined effects of snow, sleet, andfreezing rain may be sufficient to produce warning-like impacts despite no individual type meeting warning criteria. As such, the winter storm watch remains in effect and it is possible adjoining counties may be upgraded from the current advisory to a warning in later forecasts.

From the discussion above you can see the NWS is leaning on the NAM thermal profiles for this one. Presently as Al noted above the NAM is a sleet fest with several hours of heavy sleet. NAM doesn’t show much snow at outset but NWS has me 2-4” with Advisory starting at midnight, which makes me think they believe precip will start sooner than NAM accounting for their snow projection. Otherwise this is almost all sleet tomorrow staring near daybreak.

One thing that makes me buy into a later start time (closer to 7 or 8 am) is that if the cold air to our north is this strong, it will be dry as well. I could see 3 or 4 hours of virga or very light snow on the radar tonight before the dry air is overcome and anything really starts reaching the ground.

Looks like about 2-3" fell last night, the precip shield dipped below Ocean County at about 5 am, but it looks like it just started snowing again, it should stick around for another few hours here, so we could end up pushing the 4" mark by the end of the morning.

And if that change over can just stall for about 3 hrs...Ocean county on south should get another 2-3 inches tonight. We could be waking up tomorrow to 6-7" of snow otg and still have a few hours to enjoy it!

All that said, I'm officially endorsing whatever outcome tomorrow brings the most snow to the most back yards on this board...and mine already has some.

Parts of Philly and SNJ are waking up to snow this morning. That's from part of a wave that broke off the main energy in the midwest. The main wave arrives tonight to bring our area snow, sleet and rain.

Taking a look at 500mb its easy to see why a changeover will occur. The Pacific is still a nightmare for snow lovers. Phasing is happening way too early. This is a classic above normal snowfall winter for Chicago and the Midwest. They benefit from all these early phasers.

Anyway, we have weak to moderate ridging in NW Canada. This keeps a surface High Pressure locked in over SE Canada and is the reason we'll see some frozen precip instead of all rain. However, this feature eventually is forced out so we would not stay all frozen.

It looks like snow will begin 5-6am Tuesday (later closer to the coast). Here is how much snow falls before changing to sleet then rain.



This will be a nowcast to see how long the cold air holds. Just a little longer than expected could result in several inches more of snow since the precip is expected to be heavy.

I'm going with 2-4 inches of snow for NYC Metro. Slightly more N&W and less S&E, including the shore and Long Island. Precip will get lighter and possibly shut off at some point tomorrow afternoon, but it should start up again towards the evening in the form of rain.

SENJsnowman wrote:Looks like about 2-3" fell last night, the precip shield dipped below Ocean County at about 5 am, but it looks like it just started snowing again, it should stick around for another few hours here, so we could end up pushing the 4" mark by the end of the morning.

That’s awesome! Only had a coating here. Had to brush off the car and steps, but that’s all we were expecting just north of you. If I get 2-3” tonight tomorrow AM before the sleet sets in tomorrow I’ll take it. Lol. I’m hoping for a delayed changeover like November to squeeze out a little more.

Frank_Wx wrote:Parts of Philly and SNJ are waking up to snow this morning. That's from part of a wave that broke off the main energy in the midwest. The main wave arrives tonight to bring our area snow, sleet and rain.

Taking a look at 500mb its easy to see why a changeover will occur. The Pacific is still a nightmare for snow lovers. Phasing is happening way too early. This is a classic above normal snowfall winter for Chicago and the Midwest. They benefit from all these early phasers.

Anyway, we have weak to moderate ridging in NW Canada. This keeps a surface High Pressure locked in over SE Canada and is the reason we'll see some frozen precip instead of all rain. However, this feature eventually is forced out so we would not stay all frozen.

It looks like snow will begin 5-6am Tuesday (later closer to the coast). Here is how much snow falls before changing to sleet then rain.



This will be a nowcast to see how long the cold air holds. Just a little longer than expected could result in several inches more of snow since the precip is expected to be heavy.

I'm going with 2-4 inches of snow for NYC Metro. Slightly more N&W and less S&E, including the shore and Long Island. Precip will get lighter and possibly shut off at some point tomorrow afternoon, but it should start up again towards the evening in the form of rain.

Meh.Thats a lot less than the 3 to 7 NWS has forecastedOh well, with this miserable winter, to be expected.Glad the SNJ crowd cashed in last night! Think they are going to get more total for both storms!

At the risk of droning on, the “riches” continue down here. Still snowing, from moderate to light and back again. Radar now keeps ocean county in the snow thru noon!

This is a classic Shore special! Really unique micro climate down here for snow. Rags to riches I tell you! But down here, the bill ALWAYS comes due...so we better enjoy today down here. Ha ha!

If the 12z NAM is accurate, most areas north of I-78 will remain in frozen precip (sleet or frz) until late evening tomorrow with only a brief period of rain before ending overnight. I haven’t seen many storms where after the snow changes to sleet/frz it just stays in that state for several hours. Would be quite the icy slop-fest.

billg315 wrote:If the 12z NAM is accurate, most areas north of I-78 will remain in frozen precip (sleet or frz) until late evening tomorrow with only a brief period of rain before ending overnight. I haven’t seen many storms where after the snow changes to sleet/frz it just stays in that state for several hours. Would be quite the icy slop-fest.

Billg , the classic was March 1993 where I got 3 or 4 inches of heavy sleet on top of over a foot of snow.Never saw it sleet that heavy in my life and for hours.

Weather.com just downgraded my snow totals to 1-3 from 3-5 and upped the temps a tad for tomorrow. Awesome, another wet system coming...

According to the latest forecast for Hopatcong, they are calling for anywhere from 3-6 inches (possibly more if the cold air hangs on) followed by a prolonged period of sleet and potentially freezing rain, up to 1/4 inch possible.

The second half of that forecast concerns me far more than the snow. It would be very unusual to have such a prolonged period of sleet/ice and I think that's what could end being the real story up here.

Now I know that ice forecasts generally bust in this area. Is there any indication that this storm will be any different and buck that trend?

DAYBLAZER wrote:According to the latest forecast for Hopatcong, they are calling for anywhere from 3-6 inches (possibly more if the cold air hangs on) followed by a prolonged period of sleet and potentially freezing rain, up to 1/4 inch possible.

The second half of that forecast concerns me far more than the snow. It would be very unusual to have such a prolonged period of sleet/ice and I think that's what could end being the real story up here.

Now I know that ice forecasts generally bust in this area. Is there any indication that this storm will be any different and buck that trend?

Most of the models are pretty consistent on keeping the cold in place at the lower levels for prolonged sleet and freezing rain, so while its not common, I wouldn't be surprised if that's the way it goes. Where you are I think you will get a nice front end thump of snow, because the warm upper levels will take longer to move in there so the transition from snow to sleet (which may happen quickly for some people especially if this starts late) will take longer there.

docstox12 wrote:

billg315 wrote:If the 12z NAM is accurate, most areas north of I-78 will remain in frozen precip (sleet or frz) until late evening tomorrow with only a brief period of rain before ending overnight. I haven’t seen many storms where after the snow changes to sleet/frz it just stays in that state for several hours. Would be quite the icy slop-fest.

Billg , the classic was March 1993 where I got 3 or 4 inches of heavy sleet on top of over a foot of snow.Never saw it sleet that heavy in my life and for hours.

Yep, I remember that as well. I did get a long period of heavy sleet in that storm. Most of the time it seems to me once it goes to sleet it's not long before it just goes over to rain, but this may be one of those exceptions to the rule. We shall see.

billg315 wrote:

DAYBLAZER wrote:According to the latest forecast for Hopatcong, they are calling for anywhere from 3-6 inches (possibly more if the cold air hangs on) followed by a prolonged period of sleet and potentially freezing rain, up to 1/4 inch possible.

The second half of that forecast concerns me far more than the snow. It would be very unusual to have such a prolonged period of sleet/ice and I think that's what could end being the real story up here.

Now I know that ice forecasts generally bust in this area. Is there any indication that this storm will be any different and buck that trend?

Most of the models are pretty consistent on keeping the cold in place at the lower levels for prolonged sleet and freezing rain, so while its not common, I wouldn't be surprised if that's the way it goes. Where you are I think you will get a nice front end thump of snow, because the warm upper levels will take longer to move in there so the transition from snow to sleet (which may happen quickly for some people especially if this starts late) will take longer there.

Interesting. Well I'll take whatever I can get at this point. Thanks for the insight

I also see the morning commute being extremely impacted if the timing of this holds true. If this thing doesn't get going until 4-5 AM, you may have quite the situation on the roads if people leave for work under the impression that this will all quickly transition to rain. I'm thinking the I-80 and I-78 corridors are especially at risk here.

I'm ok with prolonged sleet in a winter storm (not freezing rain - I hate ice storms) if there is a good base of snow first (like that 1993 storm). Can be sort of fun to watch. But sleet itself, with no front-end snow would not be very exciting for me. lol.